Silanol Nest Engineering Facilitates Migration-Driven Trapping of Strong Lewis Acid Sites in Self-Pillared Zeolites
Self-pillared pentasil (SPP) zeolites show great promise for sustainable catalysis but face challenges in stabilizing strong Lewis acid (L-acid) sites due to weak metal-surface interactions. This study develops an “energy-driven migration” strategy to construct confined Zr-Lewis acid sites through defect engineering of boron-containing SPP precursors. By combining controlled Zr grafting with subsequent nitric acid treatment, we achieved selective deboronation to generate tailored silanol nests, directing the migration of surface Zr species into framework-confined sites. DFT calculations confirmed that silanol defects provide a strong thermodynamic driving force for Zr migration (ΔE of −14.7 eV). Through regulation of the boron content and nanosheet thickness, we achieved precise control over Zr migration while balancing efficient mass transfer and site stabilization. The optimized Zr-SPP catalyst exhibits exceptional performance in Meerwein–Ponndorf–Verley (MPV) reduction of cyclohexanone (97% conversion, TOF = 11.28 h–1), a 12-fold improvement over surface-type counterparts. Key design principles, including dissociable Zr precursors, acid-induced migration, silanol nest density optimization, and nanosheet thickness regulation, are identified as being critical for stabilizing active sites. The universality of this strategy is further validated in BEA zeolites, establishing silanol nest engineering as a general paradigm for designing durable l-acid catalysts in biomass valorization and green chemistry applications.
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